1. Field of the Invention
This invention relates to door locking mechanisms, more particularly to electric door locking mechanisms commonly known as electric strikes.
Electric strikes, also known as electric door openers, electric releases and electric release strikes, are used to control access to buildings or areas. An actuation means (e.g. an electrically driven motor or solenoid) is used to either block or release a rotatable keeper to either prevent or allow release of a door's latch bolt, to lock the door or allow it to be opened.
Typically, electric strikes have two modes, namely a “fail-secure” mode (where the door is locked with the power removed, i.e. the actuation means must be triggered to allow the door to be opened), and a “fail-safe” mode (where the door is unlocked with the power removed, i.e. the actuation means must be triggered to prevent the door from being opened). Some strikes on the market have only one-mode capability, i.e. they are either fail-secure or fail-safe, while others are dual mode, i.e. the installer can select which mode is desired at the time of installation.
2. Description of the Prior Art
One known dual-mode electric strike, for example, available as GEM model GK-300 and ROFO 2400 series models, has a solenoid mounted on a holder, which is movable within the strike housing. A blocking element is directly attached to the plunger of the solenoid, to block movement of the keeper when the strike is in its locked position. A first screw, reachable from outside the housing, cooperates with a slot in the housing, to define the path along which the holder is movable. When the first screw is tightened, it fastens the holder to the housing, i.e. the holder cannot move. First and second holes are arranged on the housing, to alternately align with a second screw, also reachable from outside the housing, so that at each end position along the holder path of movement, one of a threaded third or fourth hole, both arranged on the holder, is aligned with either the first hole or the second hole, and the second screw can be inserted into the appropriate first or second hole and screwed into the visible third or fourth hole. The installer can configure the GEM strike in either the fail-safe or fail-secure mode by selecting which holes are used. However, doing so is a tedious and tricky process, requiring proper alignment of holes, careful removal and replacement of one screw, and careful loosening (without removal) of another screw.
There is a need for an electric strike which is more readily switchable between fail-secure and fail-safe modes, and which preferably offers other advantages over prior art strikes.